 Hello friends, myself Dr. Narender Kartikar, Assistant Professor, Department of Mechanical Engineering, Valachandra Institute of Technology, Solapur. Now we are going to see the presentation and discussion on Design of Comparison Mold Part 2. At the end of this session, student will be able to understand the importance feature of design concept for compression mold design. As well the student will be able to apply design concept for mold design. The content for this presentation are introduction, compression molding, factor affecting on thermoset molding, material selection in relation to the molding conditions. Let us in brief understood the importance of plastic material, need of plastic material for manufacturing the different product and varieties of manufacturing methods for plastic part manufacturing. As we know, due to the n number of advantages properties of plastic material, nowadays it is being used as a first priority material for product manufacturing as well as the replacement of material for existing products. Considering the varieties of parameters like quantity, geometry complications and type of material being used, the varieties of plastic part manufacturing methods are developed. Out of that, one of the method is compression molding. As we know earlier, the compression molding process is going to be operated just like this. With the means of compression force, the particularly force is being applied over the charge or the blank and then it allows to flow into the mold cavity which is normally placed into the lower mold half. If we look into the stage wise, you can see over here, just to revise the compression molding process, you can see in the three stages, the material is going to be transferred into the mold cavity and how being the part geometry get the shape and geometry as exactly as that of mold cavity. This is one of the compression molding machine. At this stage of this session, are you able to recall share some of the application products that can be manufactured with the compression molding process might be seen or known earlier anywhere in real time, just enlist. I think you had enlisted the varieties of product that can be manufactured with the compression mold. This is one of the compression mold how it exactly look alike. You can see that the products are already placed which are manufactured with this particular compression mold itself. Factors affecting on thermoset molding, three important factors that must be considered in a thermoset molding are temperature, pressure, cure time, temperature, heating temperature for molding material, for thermoset, the majority of thermosetting compounds must be heated to approximately 1900 degrees Celsius for optimum cure. For various molding materials, temperature for molding the various materials can be determined by experimentation or by getting the information from the manufacturer of the particular material. Temperature variations at high temperature at low temperature and at optimum temperature, how it affects just see. Higher temperature may degrade some of the physical properties or electrical characteristics of the material and particularly in transfer molding may cause the material procure before the cavity is completely filled. High temperature may also cause blisters and burn spots on the finished articles. At the low temperature, temperature which are too low do not allow the material to flow properly and result in completely cured piece part of pure consistency thus reducing the productivity of the cycle. At the optimum temperature, there is generally an optimum temperature which produce the best flow characteristics for the particular material and cavity. Factors affecting mold temperature, the factors, the exact mold temperature not only vary the material used and the type of mold but also the geometry of the molded article and whether loose powder or preheated performs are used. Preheat temperature, need of preheat temperature because plastic are generally good heat insulating materials. Preheating of the charge is often used to shorten the time of molding. Heat temperature range are commonly 66 degree Celsius to 148 degree Celsius. Frictional heat temperature, frictional heat, another source of heat input to the plastic during the molding process is from frictional heat during the closing of the mold. In compression molding, the material is forced into the flow by the closing of the mold. Pressure, this is the second factor affecting on the thermoset molding. Filling with a thermosetting plastic required greater pressure for two basic reasons. To ensure that the plastic fills all the cavity and has relatively uniform density throughout, the pressure causes the cavity to fill and resist the tendency of internal gas to form voids or gas pockets. Pressure must be sufficient to overcome resistance of the plastic to flow. To ensure better heat transfer to the material, high pressure produces a high density which generally means faster thermal conductivity. For phenolic material, in compression molding, a pressure of 211 kg per square centimeter has been found suitable for phenolic material. But some material manufacturers recommending that 158 kg per square centimeter is sufficient. But normally this pressure is low and it is sufficient for easy flow material and a simple uncomplicated shallow mold type for molding urea and melamine material. For molding urea and melamine material, pressure of two times that needed for phenolic material are necessary approximately 315 kg per square centimeter, again adding 19.3 kg per square centimeter per centimeter of depth in excess 2.54 cm is added for material without preheat. This we had seen with this particular material example. For a medium flow material and where there is a number of average size recess, cores, shapes and pins in the molding cavity, where the material has to flow into the small intricacies and to produce a good quality hard packed and dense molding, a pressure of 211 kg per square centimeter or above is necessary. For deeper the molding simple rule, also the deeper the molding cavity the more pressure is required and a fairly simple rule is add approximately 19.3 kg per square centimeter per centimeter of depth in excess of 2.54 cm if cavity depth maximum up to 30 cm depth if cavity depth for the material without preheat. For the material with preheat the pressure approximately 70 kg per square centimeter or above is required. For deeper molding a pressure of 6.9 kg per square centimeter per centimeter depth in excess of 2.5 cm is added. Third important factor which is affecting on the thermoset molding in the case of compression molding that is cure time. Definition of cure time the period required to harden the thermoset material to partial or complete polymerization is called as the cure time. Many compounds produces parts that are hard enough blister free and apparently cured yet the polymerization operation system is not complete a post bag cycle may be required to optimize the properties. The curing time required are as follows material temperature to achieve the minimum cure time the material must be at the maximum temperature when it is loaded in the mold. Preheated by using infrared lamp, radio frequency preheaters and extruded forms from screw feed material in a heated barrel. Mold temperature the designer must have a knowledge of the recommended mold temperature for each type of material and he arrives at the maximum mold temperature and cycle that will produce a high quality part at the shortest overall cycle. Part of preheated temperature, plasticity and mold temperature must be studied to obtain the optimum mold cycle. Cross section area or wall thickness will determine the cure time required to produce the part. Parts having a thickness or cross sectional area in excess of 9.5 to 13 mm may be difficult to mold by compression when to establish minimum cure cycle transfer or injection method of molding might be better. Degree of cure, achievement of maximum molded density, achievement of proper molded part rigidity, the optimum point of molded part injection, the basis for dimension stability of molded parts are some of the advantages regarding the degree of cure. Material selection in relation to the molding condition, filler type, plasticity, pressure requirement and shrinkage, filler type, bulk factor, fiber and fillers, general purpose material, electrical or heat resisting materials are some of the parameters for filler type has to be considered while selection of material in relation to the molding condition. Pressure requirement, minimum molding pressure are desirable to hold the mold maintenance to a minimum. Excessive pressure, excessive molding, pressure extremely tight molds may cause over densification to the extent that part will expand when removed from the mold sufficient pressure however must be used to assure maximum density in the molded part. Shrinkage value, the parts must be properly density to assure consistency shrinkage value. General purpose material, glass filled materials are also to be considered separately while considering the shrinkage parameter in the material selection in relation with the molding condition. The references for these presentations are modern plastic handbook, fundamental of plastic mold design, web references CIPET institute government website, NPTEL study material. Thank you.